Due to the widespread use of wireless communication with mobile phones or the like, it is desired that the finite frequency resources be utilized by as many users as possible. In wireless communication systems for mobile phones, a plurality of base station apparatuses are connected to one another mainly by wires. Also, each of the base station apparatuses is wirelessly connected to mobile station apparatuses used by users. Although an area in which communication can be performed in wireless communication systems is limited to a range (cell) over which a radio wave reaches from each base station apparatus, arranging a plurality of base station apparatuses at different locations makes it possible to perform communication at locations within a wide range. Also, wireless communication systems of different cell arrangements or different frequency bands may be used depending on countries in which the systems are operated, carriers, communication services, or the like.
On the other hand, a mobile station apparatus may be moved to outside of a range of an area (cell) over which a radio wave reaches from a base station apparatus (to an out-of-service area). The mobile station apparatus performs processing (cell search) for searching for a base station apparatus which the mobile station apparatus can communicate with in order to become able to perform communication in the out-of-service area. The cell search is mainly composed of measurement of a reception strength and a synchronization process. After a successful cell search, the mobile station apparatus becomes able to communicate with other mobile station apparatuses.
During a cell search performed in an out-of-service area (for example, a cell search performed in response to movement from Japan to Europe), the mobile station apparatus measures the reception strength on all receivable channels in an available communication system and then performs a synchronization process in general. For this reason, the cell search has drawbacks in that it requires a long time and increases the power consumption.
Accordingly, in a communication method described in PTL 1, (1) in the case where a mobile station apparatus capable of utilizing communication systems A and B is in an out-of-service area of the communication systems, a conventional cell search (cell search for all channels) is performed as planned; (2) upon discovering, for example, a base station of the system A during the cell search, the mobile station apparatus obtains a country code (MCC: Mobile Country Code) from broadcast information, and searches lists stored in a main body storage section and an external storage section for whether or not a frequency that meets a combination of the country code and an operator is stored in the lists; and (3) if such a frequency is stored, for example, for the system B, the mobile station apparatus performs a cell search for the search-target frequency. In the case where the system B is not stored, the mobile station apparatus does not perform a cell search. As described above, the search-target frequency is limited to the frequency used by an operator that provides a communication service in that country prior to the cell search, whereby an unnecessary cell search for obtaining broadcast information of an operator that does not provide a communication service is omitted.